GitLab

The bubble implementation no longer needs the parent, instead it uses
Screen::GetDisplayForNewWindows(), which is what the code was using parent
for before.

BUG=756059
TEST=none

Change-Id: Ia58b6144cc6133027827f23ab240e094027c9a36
Reviewed-on: https://chromium-review.googlesource.com/c/1292513Reviewed-by: Shu Chen <shuchen@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601596}